2018-08-27 14:32:32 +00:00
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Thu, 12 Oct 2017 18:37:12 +0200
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Subject: [PATCH] srcu: replace local_irqsave() with a locallock
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2018-09-13 17:28:08 +00:00
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.18/older/patches-4.18.7-rt5.tar.xz
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2018-08-27 14:32:32 +00:00
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There are two instances which disable interrupts in order to become a
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stable this_cpu_ptr() pointer. The restore part is coupled with
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spin_unlock_irqrestore() which does not work on RT.
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Replace the local_irq_save() call with the appropriate local_lock()
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version of it.
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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kernel/rcu/srcutree.c | 14 +++++++++-----
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1 file changed, 9 insertions(+), 5 deletions(-)
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--- a/kernel/rcu/srcutree.c
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+++ b/kernel/rcu/srcutree.c
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@@ -37,6 +37,7 @@
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#include <linux/module.h>
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#include <linux/srcu.h>
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#include <linux/cpu.h>
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+#include <linux/locallock.h>
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#include "rcu.h"
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#include "rcu_segcblist.h"
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@@ -752,6 +753,8 @@ static void srcu_flip(struct srcu_struct
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* negligible when amoritized over that time period, and the extra latency
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* of a needlessly non-expedited grace period is similarly negligible.
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*/
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+static DEFINE_LOCAL_IRQ_LOCK(sp_llock);
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+
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static bool srcu_might_be_idle(struct srcu_struct *sp)
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{
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unsigned long curseq;
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@@ -760,13 +763,13 @@ static bool srcu_might_be_idle(struct sr
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unsigned long t;
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/* If the local srcu_data structure has callbacks, not idle. */
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- local_irq_save(flags);
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+ local_lock_irqsave(sp_llock, flags);
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sdp = this_cpu_ptr(sp->sda);
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if (rcu_segcblist_pend_cbs(&sdp->srcu_cblist)) {
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- local_irq_restore(flags);
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+ local_unlock_irqrestore(sp_llock, flags);
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return false; /* Callbacks already present, so not idle. */
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}
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- local_irq_restore(flags);
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+ local_unlock_irqrestore(sp_llock, flags);
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/*
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* No local callbacks, so probabalistically probe global state.
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@@ -844,7 +847,7 @@ void __call_srcu(struct srcu_struct *sp,
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return;
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}
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rhp->func = func;
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- local_irq_save(flags);
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+ local_lock_irqsave(sp_llock, flags);
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sdp = this_cpu_ptr(sp->sda);
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spin_lock_rcu_node(sdp);
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rcu_segcblist_enqueue(&sdp->srcu_cblist, rhp, false);
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@@ -860,7 +863,8 @@ void __call_srcu(struct srcu_struct *sp,
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sdp->srcu_gp_seq_needed_exp = s;
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needexp = true;
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}
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- spin_unlock_irqrestore_rcu_node(sdp, flags);
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+ spin_unlock_rcu_node(sdp);
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+ local_unlock_irqrestore(sp_llock, flags);
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if (needgp)
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srcu_funnel_gp_start(sp, sdp, s, do_norm);
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else if (needexp)
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